Upper Peninsula Black Bears Stayed Longer at Summer Deer Corn

STEP 1 · Two study areas

Thirty-one bears in a July and August window

Wehr and colleagues published the test in Ecology and Evolution in 2026. The animals were American black bears in Michigan's Upper Peninsula. Crystal Falls was studied from 2013 through 2015. Silver Mountain was studied from 2017 through 2019. The movement sample was 31 bears and 40 bear-years in July and August. Twenty of the 31 bears were females and 11 were males. Thirty-two bear-years had research bait inside a home range estimated for the full monitoring period. Eight did not. Site use was compared at 116 baited sites and 81 unbaited sites. The corn was put out to resemble bait used by deer hunters. Each site was followed for 21 days after the first application.

STEP 2 · Near the corn

Visits came more often and lasted much longer

Collared bears made three times as many visits to baited sites during treatment as in the before-corn and unbaited comparison. They spent eleven times as long at those baited sites. The time between consecutive visits did not differ by period.

Those ratios describe collared bears in these two areas in July and August. They are not the chance of a bear at one stand on one night. The authors could not tell whether an unmonitored bear kept other bears off a site.

STEP 3 · After dark

Visits near active corn became more nocturnal

Activity at bait sites was more nocturnal during treatment than before the corn. The same timing comparison at unbaited sites did not show that shift. Patterns before and after still overlapped heavily for both site types. Our read is that use near the corn tilted toward night while daytime use continued. A more nocturnal share does not mean the visits moved later by the clock.

A visit began when a bear came within 328 feet (100 m) of a site and ended when it left that circle. The authors chose that distance so more than one collar fix could fall inside it. They say the bear was likely near the corn rather than at it during some of those fixes. Their likely reading is that the bear stayed close to keep others away and to feed. Wehr and colleagues say an earlier camera study in the same region recorded more daytime than nighttime bear detections at bait. They suggest a difference in method may explain the gap, since a camera sees the pile and the collar rule counted every fix inside that 328-foot circle. Our read is that a camera's view cannot copy that circle or turn each photo into time spent nearby. Camera counts on the kernels will not confirm the three-times or eleven-times contrasts from these collars.

STEP 4 · Wider travel

A small comparison detected no range or step change

The authors expected smaller home ranges and shorter steps once corn was available. Home-range size, core-range size and median step length were not statistically different by period or by whether research bait sat inside the home range.

Median turning angle was smaller among bears with bait inside the range. Treatment period showed no detectable effect on turning angle. Our read is that the gap marks which bears already had research bait in range. The corn window did not account for it.

A missed difference is not proof the effect is zero. The authors say they monitored relatively few bears without access to bait and that statistical error was high. That off-bait group is 8 bear-years.

The authors say their sample was too small to compare males and females. They say males usually range wider and may visit bait more readily. Those sex statements come from other studies cited in the paper. We did not reopen them.

In the study years the authors say bear-hunter bait began in early August and could have fed bears outside the research sites. They also name recreational feeding, human refuse and livestock carcass dumps. They judge unrecorded foods equally likely inside the baited area. They add that their estimate of corn-site use could be lower than use where those other foods are absent.

Monitoring covered only July and August. The authors say bait in other seasons may produce different results.

STEP 5 · On your ground

Keep the pile and known routes as separate notes

Our test applies where deer corn is already on ground you watch. Do not put corn out to run it. If you were watching before that corn appeared, compare those days with the days after on the same routes. If you were not, compare the corn site with another place you already check.

Write what you can actually see. Note bear use at the corn and fresh sign or a sighting on routes you already know. Your notes can show whether local use continues and whether sign continues away from the pile. They cannot show that one bear's range changed. They cannot identify one bear from sign alone. They cannot reproduce the collar ratios.

Repeat bear use near the corn fits the direction of this Upper Peninsula sample. If sign keeps turning up on routes you know, keep scouting those routes. If that sign fades while bears stay at the corn, treat the fade as your own observation. These collars did not detect a smaller range, and the sign may come from more than one bear.

The paper measured GPS site use and movement. It did not measure hunting success. Bait rules vary by state and year, so check your state wildlife agency.